Electricity: motive power systems – Positional servo systems – Adaptive or optimizing systems including 'bang-bang' servos
Patent
1985-02-08
1987-03-03
Shoop, Jr., William M.
Electricity: motive power systems
Positional servo systems
Adaptive or optimizing systems including 'bang-bang' servos
318467, 318603, G05B 1300
Patent
active
046478264
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to a position loop gain control method for deciding the gain of a digital-to-analog converter, which constitutes a position loop, in such a manner that the gain of the position loop assumes a set value, the position loop being part of a spindle orientation apparatus for stopping a spindle at a prescribed orientation.
The capability of stopping a spindle at a prescribed orientation is required in a machine tool. As an example, in a machining center with ATC (automatic tool-change function), it is necessary to stop a spindle at a prescribed orientation in order to change a tool mounted on the spindle. To cut a screw hole, bore, keyway or the like into a workpiece mounted on a spindle in a turning center, it is necessary that the workpiece, namely the spindle, be brought to rest at a prescribed orientation.
To this end, various spindle orientation control apparatus have been proposed. FIG. 1 is a block diagram of a spindle orientation circuit for controlling a turning center, and FIG. 2 is an operation time chart of the same. When a turning operation is performed, a digital command velocity V.sub.c produced by an NC unit, not shown, enters a velocity command circuit 101a incorporating a DA converter and the like, where V.sub.c is converted into an analog command velocity CVA. This is then applied to a spindle motor 102 via a changeover switch 101b and a velocity control circuit 101c, thereby rotating the spindle motor. The actual velocity of the spindle motor 102 is sensed by a tachometer 103, emerging from the latter as a velocity feedback signal AVA, which is applied to the velocity control circuit 101c. The latter rotates the spindle motor 102 at the command velocity V.sub.c.
When the stage is reached at which a spindle 105 is to be brought to a stop at a prescribed orientation at the conclusion of turning machining, the NC unit, not shown, issues an orientation command ORCM and the command velocity V.sub.c becomes an initial orientation velocity (V.sub.ORi). As a result, the rotational velocity of the spindle motor 102 is decelerated down to the initial orientation velocity V.sub.ORi. When the output of an arithmetic circuit ARM, described below, attains a predetermined value after the initial orientation velocity is reached, a changeover circuit 101d changes over a movable contact of the changeover switch 101b to a contact B. An orientation controller 101e is adapted to produce a position deviation voltage RPD (analog voltage) which conforms to a deviation between a prescribed spindle position and the current spindle position. When the changeover switch 101b is changed over to the contact B, the velocity control circuit 101c produces a difference voltage between the position deviation voltage RPD and the actual velocity AVA and performs servo position control in such a manner that the position deviation voltage takes on a value of zero. When the position deviation voltage RPD reaches zero, a monitoring circuit 101f produces a spindle orientation end signal ORDEN. Thus, a position control feedback loop is constructed by the velocity control circuit 101c, spindle motor 102, position coder 104, orientation controller 101e and changeover switch 101b, with the spindle 105 being positioned at the prescribed orientation thereby. In the orientation controller 101e, a counter CNT is set to a numerical value N when the position coder 104 generates a one-revolution signal RP. Then, each time an A-phase pulse PA is generated, the status of the counter is decremented. It should be noted that N is a number, e.g., 4096, of A-phase pulses generated by the position coder 104 during one revolution of the spindle. The arithmetic circuit ARM executes the addition of a numerical value N.sub.s from the counter CNT, and a numerical value N.sub.c corresponding to a commanded spindle stopping position. DAC denotes a digital-to-analog converter (referred to as a DA converter) for generating the position deviation voltage RPD, which corresponds to a numerical value N.sub.r produc
REFERENCES:
patent: 4347471 (1982-08-01), Kohzai et al.
Bergmann Saul M.
Fanuc Ltd.
Shoop Jr. William M.
LandOfFree
Position loop gain control method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Position loop gain control method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Position loop gain control method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1018759